In the United States, women account for 20% of new HIV infections each year. Those with a heightened risk include women who engage in transactional sex or use illicit drugs. The social and economic instability (e.g., housing, financil) experienced by some women may drive initiation of or escalate illicit drug use and unprotected transactional sex, amplifying the risk for HIV infection. Female exotic dancers are an important subgroup of vulnerable women who experience socioeconomic instability and commonly engage in sex- and drug-related HIV risk behaviors through their work at exotic dance clubs. Through a sample of exotic dancers in Baltimore, Maryland, the purpose of the proposed research is to investigate the relationship between socioeconomic instability, illicit drug use, an unprotected transactional sex among vulnerable women. Specifically, the study aims to develop a reliable and valid tool for measuring socioeconomic instability among vulnerable women at heightened risk for HIV. Using this tool, the longitudinal association between socioeconomic instability, drug use, and unprotected transactional sex will be evaluated. These findings will be informed by a qualitative exploration of the nature and context of socioeconomic instability and its effect on sex- and drug-related HIV risk behaviors. The proposed research will use quantitative and qualitative data from a parent study that will follow a cohort of exotic dancers for six months. Longitudinal survey data will be used to develop the summary measure of socioeconomic instability and track changes in instability, drug use, and unprotected transactional sex. A series of qualitative interviews will explore dancers' perceptions of instabilty and uncover narratives about socioeconomic instability and HIV risk behavior. The proposed research offers a rich training opportunity to build skills in measurement and mixed methods while addressing NIDA's HIV/AIDS research priorities and strategic goals. Findings will advance knowledge regarding social and economic determinants of drug use and risky sexual behavior, ultimately informing future structural-level prevention and care strategies for people both at risk for and living with HIV.